Aquarium Lighting

There is little role for incandescent lighting in growing plants, and least
when dealing with aquaria. Some may even come with incandescent
lights, though these do little: to provide enough light to grow plants, you'd
produce enough heat to seriously harm, often kill the fish. Light quality is
poor, and operating costs are high. Avoid them.

Fluorescent lights again may be used to good effect, and again, should be
changed every six months as their output drops. Cool white tubes, or better, using both a cool white and a warm white bulb provides reasonable
light; using plant growth lights in combination with daylight bulbs gives
very good light quality for the price. As the depth of the aquarium increases beyond 18", increase the number of tubes used to provide light.

Keep in mind the light needs of fish as well as those of the plants to be
grown in the aquarium: some require high light levels, best provided by
two or more wide-spectrum daylight tubes, in the 7500K range; a plant
growth fluorescent may be mixed in though the daylight tubes themselves
often suffice for good plant growth. For fish with low light needs, one or
two plant fluorescents should suffice.

Tri-phosphor tubes, with sharp spikes in red, green and blue wavelengths, can be effectively combined with plant growth lights. Typically, a
very bright, white light is produced; those with greater amounts of red, i.e.
in the 3000 to 4000K colour temperature range, are best for aquarium settings. The Triton variant on these tubes is useful especially in growing
anemones and corals, and are interesting in that their light output does
not significantly degrade over time, unlike other fluorescents. Generic triphosphor tubes are relatively inexpensive; Triton tubes, however, are not.

Some tubes are used in very limited roles, i.e. the actinic tubes that emit
light especially in the blue wavelengths, to enhance growth of anemones,
corals, and algae; these are useless in growing freshwater aquarium
plants. Their price, also, is substantial.

Finally, in some aquarium applications, intense light levels are required.
High output fluorescents may sometimes be used, as may High Intensity Discharge lamps.
Since this takes us well beyond the scope of the average home aquarium,
no more is said on this subject, here.